Effect of temperature on motor responses in organophosphate intoxication

We studied the effect of temperature on median motor responses in a 41-year-old man with organophosphate intoxication. At 32 degrees C, a normal amplitude compound motor action potential (CMAP) and a smaller spontaneous repetitive discharge (SRMAP) were present. With warming to 39 degrees C, the CMAP amplitude decreased 20%, while the SRMAP amplitude decreased 33%. With cooling to 14 degrees C, the CMAP amplitude decreased 9%, while the SRMAP became unobtainable. Possible mechanisms for these findings are discussed.